The sound from an electric stringed instrument starts with metallic strings vibrating near a pickup. Pickups are essentially magnetic coils, each consisting of a small magnet wrapped in fine copper wire. When a metallic object (such as an electric guitar string for example) is vibrated above the magnetic coil, the magnetic field is disturbed and an electrical current is produced. This current passes from the pickup to the instrument's output jack and then to an amplifier and speaker to produce the sound associated with the electric instrument.
Accordingly, a traditional electric guitar setup requires:                An electric guitar;        An amplifier and speakers;        Guitar cable from guitar to amplifier;        Mains power lead from amplifier to power outlet; and optionally        Effects pedals or board with power supply cables.        
Since the introduction of smart devices, and in particular the Apple iPhone™, software developers began producing ‘guitar apps’ which are software programs able to process and record the output signal from an electric guitar. Guitar apps are used in conjunction with a guitar audio interface, which is an electronic hardware device that facilitates electrical connection of a guitar to smartphone. The output cable which normally couples the electric guitar to an amplifier is instead coupled to the guitar audio interface and the guitar audio interface has an output cable or dock connector which is coupled to the smart device. There is typically an audio out electrical connection on the guitar interface to electrically connect to either headphones or an audio amplifier.
One of the core functions of guitar apps is to process the signal from the guitar before it is sent to an amplifier or headphones. Signal processing can be used to accurately recreate the sound or tone (timbre) of classic amplifiers such as those produced by Fender or Marshall, or the sound or tone of guitar effect pedals to produce, for example echo/digital delay, revert, distortion, phaser etc.
Some of the functions provided by guitar apps include; amplifier simulation/modelling; guitar effects pedal simulation/modelling; speaker cabinet, simulation/modelling; multi-track recording and audio editing; song or backing track playback using songs stored on the smart device; and drum sequencing.
The advantage and appeal of the new guitar apps that all of this functionality is now contained on the user's smart device and is thus highly portable. When combined with an audio amplifier and speakers, guitar apps effectively turn a smartphone into a full electric guitar setup and recording studio. Before the introduction of guitar apps all of this functionality would have had to be provided by traditional guitar hardware such as guitar amplifiers, effects pedals, and the like, connected to a computer which is running audio editing software programs.
Although guitar apps allow the user to do away with a number of components from the electric guitar setup, thus making a more portable setup, it is still an inconveniently large amount of equipment to transport. The present invention seeks to provide an improved musical instrument which overcomes at least some of the remaining difficulties.